The present invention relates, in general, to watthour meters and, more specifically, to watthour meter sockets mounted in enclosures.
Power disconnect switches are used in a number of applications, such as utility watthour meter, relay, instrument transducer and control system calibration, disconnecting, troubleshooting and testing.
In the electric utility application, watthour meters are commonly employed to measure electrical power consumption at a residential or commercial establishment. A cabinet is typically mounted on an outside wall of the residence or building and contains a meter socket having pairs of line and load contacts which are connected to electric power line conductors extending from the utility power network and electric load conductors connected to the residential or building establishment power distribution network. The contacts in the socket receive blade terminals on a plug-in watthour meter to complete an electric circuit through the meter between the line and load terminals in the cabinet for the measurement of electrical power consumption.
Current transformer or CT rated watthour meters and socket adapters are employed in high current applications. In such an application, current transformers are coupled to the line and load conductors and have their output leads connected to terminals in a current transformer or CT rated watthour meter socket adapter. A low current rated watthour meter is then plugged into the socket adapter or socket to measure consumed at the building site.
In addition, potential coils in a watthour meter may also be connected by potential blade terminals to potential blade contacts mounted in the socket or socket adapter and connected by individual conductors to terminals mounted in the terminal portion of the socket adapter.
However, with current transformer rated socket adapters or sockets, it is necessary to short circuit the line and load terminals when the watthour meter is removed from the socket for replacement or testing. Heretofore, test switch devices have been incorporated into the CT rated socket to provide the necessary short circuit or bypass feature.
Exemplary test switches are made by Meter Devices Company, Inc., of Canton, Ohio. Such test switches are typically mounted in a watthour meter socket immediately below a watthour meter or watthour meter/socket adapter. The test switches are generally in the form of single throw, knife-type switches which are provided in multiples ganged together into one assembly; but each electrically connected between one line contact and one load contact in the socket. Once an optional socket cover is removed, the test switches can be operated as desired to provide the necessary bypass connection between the line and load contacts and conductors prior to removing the watthour meter from the socket for testing, recalibration, replacement, etc.
However, wiring connections are required to be made between the bottom mounted terminals on a typical watthour meter socket, such as the watthour meter socket adapter shown in U.S. Pat. No. 5,853,300, and assigned to the assignee of the present invention, and the individual terminals on the meter test switches. The two terminals between each jaw contact and each meter test switch introduce a voltage drop and a resulting power drop in the watthour meter circuitry. In addition, the extra wiring connections and conductors add cost to the watthour meter/meter test switch assembly.
The voltage drop across the terminal block connections also causes the loss of metered power. In the current circuits where a current transformer is employed, the extra terminal connections place a larger load on the current transformer which must then work harder. This effects the accuracy of the current transformer output and may require larger diameter or gauge conductors between the current transformer and the line and load terminals in the watthour meter socket.
In an attempt to address these disadvantages, Ekstrom Industries, Inc., has previously sold a pre-wired meter socket and test switch assembly including a meter socket with internal mounted meter jaws which is mounted on a planar plate. The meter test switch assembly was also mounted on the plate immediately below the jaw portion of the meter socket. Conductors from the individual jaw contacts were connected directly to the meter test switch terminals thereby eliminating at least one set of terminal blocks and the wires and associated labor required therefore.
However, this apparatus us difficult to use since the one-piece assembly is bulky and difficult to ship. Further, the utility company is required to use the meter test switch and meter socket shipped by the manufacturer. This results in duplicate parts since the utility frequently had its own supply of meter test switches or a meter test switch was already mounted in a particular socket enclosure.
Thus, it would be desirable to provide a meter socket usable with a meter test switch apparatus which overcomes the difficulties encountered with the use of previously devised meter socket and meter test switch combinations.
The present invention is a meter socket for mounting in an enclosure and connectable to a meter test switch remotely located from the meter socket.
In one aspect of the invention, the meter socket includes a housing having a base and a sidewall extending from the base. The sidewall has a generally annular mounting flange extending radially outward from one end of at least a portion of the sidewall, the mounting flange adapted for interconnection with a mating mounting flange on a watthour meter. Jaws are mounted in the base of the housing for receiving blade terminals of a watthour meter. Electrical conductors are disposed with one end in the housing connected to one of the jaws. The electrical conductors extend externally of the housing to another end adapted for connection to a remotely located meter test switch device.
In one aspect of the invention, the conductors extend from the housing in at least one and preferably two separate individually tied together groups or bundles to facilitate routing of the conductors to the meter test switch.
In another aspect, the conductors have unique exterior color coding to identify each specific conductor to facilitate connection to the appropriate meter test switch terminals.
The housing includes a filler extending between lower walls projecting from a portion of the annular sidewall of the housing. In one aspect of the invention, the filler includes a aperture which extends through the filler and an adjacent portion of the annular sidewall of the housing. This aperture facilitates the passage of electrical cable or conductors extending from a watthour meter through the socket housing when the watthour meter is mounted on the mounting flange of the housing.
In another aspect, the apparatus includes a housing having a watthour meter receiving portion and a wire guide portion spaced from the watthour meter receiving portion. A plurality of jaw-type electrical contacts are mounted in the watthour meter receiving portion, each jaw contact receiving a blade terminal of a watthour meter in a snap-in connection. Electrical conductors are connected to the jaw contacts and extend through the wire guides to external connections on an electrical component.
Means are formed on or mounted in the housing for substantially completely covering the electrical conductors and the contacts in the housing. The covering means preferably comprises the housing being formed of first and second plates, one plate having an annular side wall extending outward therefrom. The first and second plates are spaced apart, when joined together, to define an interior cavity. The electrical conductors are disposed in the cavity and are completely enclosed by the first and second plates and the annular side wall. A plurality of hollow receptacles are formed in the first plate and extend outward from the first plate. The interior of each receptacle opens to the interior cavity between the first and second plates and receives a jaw contact therein. A slot is formed in each receptacle for receiving a blade terminal of a watthour meter therethrough to enable the blade terminal to be inserted into an underlying jaw contact. Each receptacle is formed with closed side walls and an outer end wall to completely surround all portions of the jaw contact housed therein.
A plurality of potential jaw contacts are also mounted in the socket adapter housing. The potential jaw contacts are disposed in separate receptacles formed in the first plate of the housing.
Each potential jaw contact includes, by example, a base, first and second spaced, substantially co-planar, angularly bent jaws extending from the base, and a third angularly bent jaw extending from the base and disposed between the first and second jaws, an outer end of the third jaw spaced from outer ends of the first and second jaws to define a watthour meter blade terminal receiving slot between the first, second and third jaws. Means are connected to the base for connecting a first external electrical conductor to the base. Means are also carried with the base for electrically connecting one of a plurality of second external electrical conductors to each potential jaw contact.
The terminals each include a collar having a through bore and an aperture intersecting the through bore, and a terminal clip having a first and second ends, the first end disposed in the through bore in the collar. The terminal clip is formed by a first pair of tabs formed on the second end of the terminal clip, the pair of tabs defining an aperture adapted to receive one electrical conductor, and a second pair of tabs formed on the terminal clip intermediate the first and second ends of the terminal clip.
The wire guide portion includes a plurality of spaced dividers formed on the first plate.
The meter socket of the present invention provides many unique solutions to the use of previously devised meter sockets and meter test switch combinations. Providing the meter socket housing with an open end enables the conductors connected to each of the individual jaws in the socket housing to extend through the open end of the housing and routed to a connection at an opposite end to terminals on a remotely located meter test switch. This enables the meter socket of the present invention to be easily used with existing meter test switch assemblies or with any meter test switch assembly selected by a utility. The conductors extending between the meter test switch and the meter socket may be easily routed in any configuration. Arranging the conductors in at least one and preferably two tied together groups or bundles facilitates the easy routing of the electrical conductors between the meter socket and the meter test switch assembly.
An aperture may be formed in the meter socket housing and adjacent portion of the annular sidewall on the housing to facilitate the passage of data and telephone cable or other electrical conductors extending outward from a watthour meter through the socket housing without sharp bends. The enables such cable or conductors to be easily passed through the socket housing without damage and, further, easily connected to externally located devices or circuits.
Finally, the provision of unique color coded insulated jackets on each of the conductors facilitates the connection of the conductors to the appropriate terminal on the meter test switch assembly.